HST observations of QZ Lib reveal a very cool white dwarf

thanks so much for your help with the HST observations of QZ Lib! The moon made it tough to get measurements during the critical 24 hours before HST would slew to the star, but it all worked out well.

The COS far-ultraviolet spectrum shows a very cool white dwarf, exactly what we were after. This is unusual, given the relatively long orbital period, it implies as that at least for the past few 10000 years or so the accretion rate has been much lower than that of most other CVs with orbital periods in this range ... but it may even be that this is an extremely old and evolved CV. The other puzzling fact is the set of emission lines it displays, that is unique among all the systems we observed in this campaign, and in the past years more generally. Definitely a very interesting catch, that will keep us busy for a while.

Best wishes, and thanks again for making these HST observations possible.

Althought I didn't contribute to this campaign (I did on 2 other HST's last year) I'll add this to my observing list and watch it til it goes below my horizon in August. Sounds like an astrophysically cool object and hope to see some ApJ papers on this!